Could someone elaborate on what the correct parameters of the empirical test would be?

Identify a stimulus that prompts the undesired attachment response. Most simply talking about a circumstance where the incongruence between the desired outcome and the actual outcome causes emotional distress of some kind.

Then, as a primitive metric you could wire them and measure their pulse, blood pressure and skin conductivity. Do this before and after a few weeks of meditation. Contrast with a control group that does nothing and another that does an alternative form of personal development.

(That's just what I thought of in the time it took me to type as someone with absolutely no qualification for doing that sort of study. If I knew what I was doing and had time to make a plan and new what the typical protocol in this kind of situation was I would likely do something entirely different.)